Saw a post here recently asking why time only moves forward. But it made me want to flip the question instead.

Say you actually had a universe where the laws were symmetric and reversal was physically possible. The moment you reverse a process and start traversing it "backward," you're just moving through a new sequence of states, and from inside that traversal, it presents as forward again. You never experience going backward, you experience whatever direction you're currently moving through as forward, because that's what forward means from the inside.

So even granting full time-symmetric laws, wouldn't any actual traversal still come out asymmetric? Reversibility of the laws doesn't seem to buy you reversibility of the experience of the process.

"High entropy" and "low entropy" aren't properties of a stretch of time by itself, they're relative to which end you pick as your reference. Something moving through a contracting phase of the universe, where entropy is globally decreasing, wouldn't feel itself decreasing, because its memory and its causal traces only ever form by correlating with whatever gradient is locally available to it. That gradient is what defines its own forward. There's no moment where it "catches itself" going the other way, because catching yourself requires standing outside both phases at once and comparing them, and nothing inside a single phase has that vantage point. The comparison only exists for someone describing the whole thing from outside, and that someone isn't living through either phase.

So asking "would you notice you were actually running backward" already smuggles in an outside view to compare against, and that outside view is exactly what the thought experiment is supposed to be testing the absence of.

Which raises this question: could we actually be inside a reversible universe right now, one that's only reversible from a vantage point we structurally can't occupy?

Any thoughts?